Method of fabricating optical devices using laser treatment

ABSTRACT

A method for forming optical devices. The method includes providing a gallium nitride substrate member having a crystalline surface region and a backside region. The method also includes subjecting the backside region to a laser scribing process to form a plurality of scribe regions on the backside region and forming a metallization material overlying the backside region including the plurality of scribe regions. The method removes at least one optical device using at least one of the scribe regions.

BACKGROUND OF THE INVENTION

The present invention is directed to optical devices and relatedmethods. More particularly, the present invention provides a method anddevice for emitting electromagnetic radiation using nonpolar galliumcontaining substrates such as GaN, MN, InN, InGaN, AlGaN, and AlInGaN,and others. Merely by way of example, the invention can be applied tooptical devices, lasers, light emitting diodes, solar cells,photoelectrochemical water splitting and hydrogen generation,photodetectors, integrated circuits, and transistors, among otherdevices.

In the late 1800's, Thomas Edison invented the light bulb. Theconventional light bulb, commonly called the “Edison bulb,” has beenused for over one hundred years for a variety of applications includinglighting and displays. The conventional light bulb uses a tungstenfilament enclosed in a glass bulb sealed in a base, which is screwedinto a socket. The socket is coupled to an AC power or DC power source.The conventional light bulb can be found commonly in houses, buildings,and outdoor lightings, and other areas requiring light or displays.Unfortunately, drawbacks exist with the conventional Edison light bulb:

-   -   The conventional light bulb dissipates much thermal energy. More        than 90% of the energy used for the conventional light bulb        dissipates as thermal energy.    -   Reliability is an issue since the conventional light bulb        routinely fails often due to thermal expansion and contraction        of the filament element.    -   Light bulbs emit light over a broad spectrum, much of which does        not result in bright illumination or due to the spectral        sensitivity of the human eye.    -   Light bulbs emit in all directions and are not ideal for        applications requiring strong directionality or focus such as        projection displays, optical data storage, or specialized        directed lighting.

In 1960, the laser was first demonstrated by Theodore H. Maiman atHughes Research Laboratories in Malibu. This laser utilized asolid-state flashlamp-pumped synthetic ruby crystal to produce red laserlight at 694 nm. By 1964, blue and green laser output was demonstratedby William Bridges at Hughes Aircraft utilizing a gas laser designcalled an Argon ion laser. The Ar-ion laser utilized a noble gas as theactive medium and produce laser light output in the UV, blue, and greenwavelengths including 351 nm, 454.6 nm, 457.9 nm, 465.8 nm, 476.5 nm,488.0 nm, 496.5 nm, 501.7 nm, 514.5 nm, and 528.7 nm. The Ar-ion laserhad the benefit of producing highly directional and focusable light witha narrow spectral output, but the efficiency, size, weight, and cost ofthe lasers were undesirable.

As laser technology evolved, more efficient lamp pumped solid statelaser designs were developed for the red and infrared wavelengths, butthese technologies remained a challenge for blue and green and bluelasers. As a result, lamp pumped solid state lasers were developed inthe infrared, and the output wavelength was converted to the visibleusing specialty crystals with nonlinear optical properties. A green lamppumped solid state lasers had 3 stages: electricity powers lamp, lampexcites gain crystal which lases at 1064 nm, 1064 nm goes into frequencyconversion crystal which converts to visible 532 nm. The resulting greenand blue lasers were called “lamped pumped solid state lasers withsecond harmonic generation” (LPSS with SHG) and were more efficient thanAr-ion gas lasers, but were still too inefficient, large, expensive,fragile for broad deployment outside of specialty scientific and medicalapplications. Additionally, the gain crystal used in the solid statelasers typically had energy storage properties which made the lasersdifficult to modulate at high speeds which limited its broaderdeployment.

To improve the efficiency of these visible lasers, high power diode (orsemiconductor) lasers were utilized. These “diode pumped solid statelasers with SHG” (DPSS with SHG) had 3 stages: electricity powers 808 nmdiode laser, 808 nm excites gain crystal which lases at 1064 nm, 1064 nmgoes into frequency conversion crystal which converts to visible 532 nm.The DPSS laser technology extended the life and improved the efficiencyof the LPSS lasers, and further commercialization ensue into more highend specialty industrial, medical, and scientific applications. However,the change to diode pumping increased the system cost and requiredprécised temperature controls, leaving the laser with substantial size,power consumption while not addressing the energy storage propertieswhich made the lasers difficult to modulate at high speeds.

As high power laser diodes evolved and new specialty SHG crystals weredeveloped, it became possible to directly convert the output of theinfrared diode laser to produce blue and green laser light output. These“directly doubled diode lasers” or SHG diode lasers had 2 stages:electricity powers 1064 nm semiconductor laser, 1064 nm goes intofrequency conversion crystal which converts to visible 532 nm greenlight. These lasers designs are meant to improve the efficiency, costand size compared to DPSS-SHG lasers, but the specialty diodes andcrystals required make this challenging. Additionally, while thediode-SHG lasers have the benefit of being directly modulate-able, theysuffer from severe sensitivity to temperature which limits theirapplication.

From the above, it is seen that techniques for improving optical devicesis highly desired.

BRIEF SUMMARY OF THE INVENTION

According to the present invention, techniques related generally tooptical devices are provided. More particularly, the present inventionprovides a method and device for emitting electromagnetic radiationusing nonpolar gallium containing substrates such as GaN, MN, InN,InGaN, AlGaN, and AlInGaN, and others. In a specific embodiment, theelectromagnetic radiation has a wavelength of 395, 405, 450, 485, 500,520, nanometers and others. Merely by way of example, the invention canbe applied to optical devices, lasers, light emitting diodes, solarcells, photoelectrochemical water splitting and hydrogen generation,photodetectors, integrated circuits, and transistors, among otherdevices.

In a specific embodiment, the present invention provides an opticaldevice, e.g., laser, LED. The device comprises a gallium nitridesubstrate member having a crystalline surface region and a backsideregion. In a preferred embodiment, the surface region is configured as anon-polar or semipolar orientation, but can be others. The device has atleast one scribe line configured from at least a laser process formedwithin a spatial region of the backside region. A metallization materialIS overlying the backside region and one or more portions of the scribeline according to one or more embodiments.

In a specific embodiment, the present invention provides a method forforming optical devices. The method includes providing a gallium nitridesubstrate member having a crystalline surface region and a backsideregion. The method also includes subjecting the backside region to alaser scribing process to form a plurality of scribe regions on thebackside region and forming a metallization material overlying thebackside region including the plurality of scribe regions. The methodremoves at least one optical device using at least one of the scriberegions. In a specific embodiment, the scribe process is followed by abreak process to remove and separate the optical device from a remainingportion of the substrate member. In an alternative embodiment, the laserscribing process may be performed after forming metallization materialoverlying the backside region.

In an alternative specific embodiment, the present invention provides amethod for forming optical devices, e.g., lasers, LEDs. The methodincludes providing a gallium nitride substrate member having acrystalline surface region and a backside region in a specificembodiment. The crystalline surface region configured in a non-polar orsemi-polar orientation or others. The method also includes forming oneor more active regions configured to emit electromagnetic radiation foran optical device. The method forms a metallization material overlying asurface region, e.g., backside, frontside, edges, combinations. Themethod includes subjecting the surface region to a laser treatmentprocess to change an operating voltage of the optical device from afirst value to a second value, which is less than the first value by atleast 10 percent, but can be other values. The method causes formationof at least one scribe region on the surface region. The method includesremoving at least the optical device using at least the scribe region.

Benefits are achieved over pre-existing techniques using the presentinvention. In particular, the present invention enables a cost-effectiveoptical device for laser applications. In a specific embodiment, thepresent optical device can be manufactured in a relatively simple andcost effective manner. Depending upon the embodiment, the presentapparatus and method can be manufactured using conventional materialsand/or methods according to one of ordinary skill in the art. Thepresent laser device uses a nonpolar gallium nitride material capable ofachieve a laser having a wavelength of about 400 nanometers and 405nanometers can greater, among others. In other embodiments, the deviceand method can achieve a wavelength of about 500 nanometers and greaterincluding 520 nanometers. In a preferred embodiment, the resulting laseror light emitting diode device has an improved contact, which is lowerin resistance and provides a lower voltage drop through the device.Depending upon the embodiment, one or more of these benefits may beachieved. These and other benefits may be described throughout thepresent specification and more particularly below.

The present invention achieves these benefits and others in the contextof known process technology. However, a further understanding of thenature and advantages of the present invention may be realized byreference to the latter portions of the specification and attacheddrawings. That is, the description has been provided in terms of anoptical device, but other devices can also be used. Such other devicesinclude electrical devices, mechanical devices, and any combinations. Ofcourse, there can be other variations, modifications, and alternatives.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified perspective view of a laser device fabricated ona nonpolar substrate according to an embodiment of the presentinvention;

FIG. 2 is a detailed cross-sectional view of a laser device fabricatedon a nonpolar substrate according to an embodiment of the presentinvention;

FIG. 3 is a cross-sectional view photograph of an c-direction cleavedfacet for a laser device according to an embodiment of the presentinvention;

FIG. 4 is a top-view diagram of a laser device according to anembodiment of the present invention;

FIGS. 5 to 12 illustrate a simplified backend processing method of alaser device according to one or more embodiments of the presentinvention;

FIGS. 13 to 18 illustrate a simplified laser scribe process forimproving contact regions of an optical device according to one or moreembodiments of the present invention; and

FIGS. 19 and 20 are simplified diagram illustrating experimental resultsof a laser scribing process for contact formation according to one ormore examples of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, techniques related generally tooptical devices are provided. More particularly, the present inventionprovides a method and device for emitting electromagnetic radiationusing non-polar gallium containing substrates such as GaN, MN, InN,InGaN, AlGaN, and AlInGaN, and others. Merely by way of example, theinvention can be applied to optical devices, lasers, light emittingdiodes, solar cells, photoelectrochemical water splitting and hydrogengeneration, photodetectors, integrated circuits, and transistors, amongother devices.

FIG. 1 is a simplified perspective view of a laser device 100 fabricatedon a non-polar substrate according to an embodiment of the presentinvention. This diagram is merely an example, which should not undulylimit the scope of the claims herein. One of ordinary skill in the artwould recognize other variations, modifications, and alternatives. Asshown, the optical device includes a gallium nitride substrate member101 having a nonpolar crystalline surface region characterized by anorientation of about −6 degrees to about 6 degrees towards (000-1) andless than about 0.5 degrees towards (11-20). In a specific embodiment,the gallium nitride substrate member is a bulk GaN substratecharacterized by having a nonpolar crystalline surface region, but canbe others. In a specific embodiment, the bulk nitride GaN substratecomprises nitrogen and has a surface dislocation density below 10⁵ cm⁻².The nitride crystal or wafer may comprise Al_(x)In_(y)Ga_(1-x-y)N, where0≦x, y, x+y≦1. In one specific embodiment, the nitride crystal comprisesGaN. In one or more embodiments, the GaN substrate has threadingdislocations, at a concentration between about 10⁵ cm⁻² and about 10⁸cm⁻², in a direction that is substantially orthogonal or oblique withrespect to the surface. As a consequence of the orthogonal or obliqueorientation of the dislocations, the surface dislocation density isbelow about 10⁵ cm⁻².

In a specific embodiment, the device has a laser stripe region formedoverlying a portion of the nonpolar crystalline orientation surfaceregion. In a specific embodiment, the laser stripe region ischaracterized by a cavity orientation is substantially parallel to thec-direction. In a specific embodiment, the laser strip region has afirst end 107 and a second end 109.

In a preferred embodiment, the device has a first cleaved c-face facetprovided on the first end of the laser stripe region and a secondcleaved c-face facet provided on the second end of the laser striperegion. In one or more embodiments, the first cleaved c-facet issubstantially parallel with the second cleaved c-facet. Mirror surfacesare formed on each of the cleaved surfaces. The first cleaved c-facetcomprises a first mirror surface. In a preferred embodiment, the firstmirror surface is provided by a scribing and breaking process. Thescribing process can use any suitable techniques, such as a diamondscribe or laser scribe or combinations. In a specific embodiment, thefirst mirror surface comprises a reflective coating. The reflectivecoating is selected from silicon dioxide, hafnia, and titaniatantalumpentoxidezirconia, including combinations, and the like. Depending uponthe embodiment, the first mirror surface can also comprise ananti-reflective coating. Of course, there can be other variations,modifications, and alternatives.

Also in a preferred embodiment, the second cleaved c-facet comprises asecond mirror surface. The second mirror surface is provided by ascribing and breaking process according to a specific embodiment.Preferably, the scribing is diamond scribed or laser scribed or thelike. In a specific embodiment, the second mirror surface comprises areflective coating, such as silicon dioxide, hafnia, titania, tantalum,pentoxide, zirconia, combinations, and the like. In a specificembodiment, the second mirror surface comprises an anti-reflectivecoating. Of course, there can be other variations, modifications, andalternatives.

In a specific embodiment, the laser stripe has a length and width. Thelength ranges from about 50 microns to about 3000 microns. The stripalso has a width ranging from about 0.5 microns to about 50 microns, butcan be other dimensions. In a specific embodiment, the width issubstantially constant in dimension, although there may be slightvariations. The width and length are often formed using a masking andetching process, which are commonly used in the art. Further details ofthe present device can be found throughout the present specification andmore particularly below.

In a specific embodiment, the device is also characterized by aspontaneously emitted light is polarized in substantially perpendicularto the c-direction. That is, the device performs as a laser or the like.In a preferred embodiment, the spontaneously emitted light ischaracterized by a polarization ratio of greater than 0.1 to about 1perpendicular to the c-direction. In a preferred embodiment, thespontaneously emitted light characterized by a wavelength ranging fromabout 405 nanometers to yield a blue emission, a green emission, andothers. In a preferred embodiment, the spontaneously emitted light ishighly polarized and is characterized by a polarization ratio of greaterthan 0.4. Of course, there can be other variations, modifications, andalternatives. Further details of the laser device can be foundthroughout the present specification and more particularly below.

FIG. 2 is a detailed cross-sectional view of a laser device 200fabricated on a nonpolar substrate according to an embodiment of thepresent invention. This diagram is merely an example, which should notunduly limit the scope of the claims herein. One of ordinary skill inthe art would recognize other variations, modifications, andalternatives. As shown, the laser device includes gallium nitridesubstrate 203, which has an underlying n-type metal back contact region201. In a specific embodiment, the metal back contact region is made ofa suitable material such as those noted below and others. Furtherdetails of the contact region can be found throughout the presentspecification and more particularly below.

In a specific embodiment, the device also has an overlying n-typegallium nitride layer 205, an active region 207, and an overlying p-typegallium nitride layer structured as a laser stripe region 209. In aspecific embodiment, each of these regions is formed using at least anepitaxial deposition technique of metal organic chemical vapordeposition (MOCVD), molecular beam epitaxy (MBE), or other epitaxialgrowth techniques suitable for GaN growth. In a specific embodiment, theepitaxial layer is a high quality epitaxial layer overlying the n-typegallium nitride layer. In some embodiments the high quality layer isdoped, for example, with Si or O to form n-type material, with a dopantconcentration between about 10¹⁶ cm⁻³ and 10²⁰ cm⁻³.

In a specific embodiment, an n-type Al_(u)In_(v)Ga_(1-u-v)N layer, where0≦u, v, u+v≦1, is deposited on the substrate. In a specific embodiment,the carrier concentration may lie in the range between about 10¹⁶ cm⁻³and 10²⁰ cm⁻³. The deposition may be performed using metalorganicchemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). Ofcourse, there can be other variations, modifications, and alternatives.

As an example, the bulk GaN substrate is placed on a susceptor in anMOCVD reactor. After closing, evacuating, and back-filling the reactor(or using a load lock configuration) to atmospheric pressure, thesusceptor is heated to a temperature between about 1000 and about 1200degrees Celsius in the presence of a nitrogen-containing gas. In onespecific embodiment, the susceptor is heated to approximately 1100degrees Celsius under flowing ammonia. A flow of a gallium-containingmetalorganic precursor, such as trimethylgallium (TMG) ortriethylgallium (TEG) is initiated, in a carrier gas, at a total ratebetween approximately 1 and 50 standard cubic centimeters per minute(sccm). The carrier gas may comprise hydrogen, helium, nitrogen, orargon. The ratio of the flow rate of the group V precursor (ammonia) tothat of the group III precursor (trimethylgallium, triethylgallium,trimethylindium, trimethylaluminum) during growth is between about 2000and about 12000. A flow of disilane in a carrier gas, with a total flowrate of between about 0.1 and 10 sccm is initiated.

In a specific embodiment, the laser stripe region is made of the p-typegallium nitride layer 209. In a specific embodiment, the laser stripe isprovided by an etching process selected from dry etching or wet etching.In a preferred embodiment, the etching process is dry, but can beothers. As an example, the dry etching process is an inductively coupledprocess using chlorine bearing species or a reactive ion etching processusing similar chemistries. Again as an example, the chlorine bearingspecies are commonly derived from chlorine gas or the like. The devicealso has an overlying dielectric region, which exposes 213 contactregion. In a specific embodiment, the dielectric region is an oxide suchas silicon dioxide or silicon nitride, but can be others. The contactregion is coupled to an overlying metal layer 215. The overlying metallayer is a multilayered structure containing gold and platinum (Pt/Au),but can be others. Of course, there can be other variations,modifications, and alternatives.

In a specific embodiment, the laser device has active region 207. Theactive region can include one to twenty quantum well regions accordingto one or more embodiments. As an example following deposition of then-type Al_(u)In_(v)Ga_(1-u-v)N layer for a predetermined period of time,so as to achieve a predetermined thickness, an active layer isdeposited. The active layer may comprise a single quantum well or amultiple quantum well, with 1-20 quantum wells. The quantum wells maycomprise InGaN wells and GaN barrier layers. In other embodiments, thewell layers and barrier layers comprise Al_(w)In_(x)Ga_(1-w-x)N andAl_(y)In_(z)Ga_(1-y-z)N, respectively, where 0≦w, x, y, z, w+x, y+z≦1,where w<u, y and/or x>v, z so that the bandgap of the well layer(s) isless than that of the barrier layer(s) and the n-type layer. The welllayers and barrier layers may each have a thickness between about 1 nmand about 40 nm. In another embodiment, the active layer comprises adouble heterostructure, with an InGaN or Al_(w)In_(x)Ga_(1-w-x)N layerabout 10 nm to 100 nm thick surrounded by GaN or Al_(y)In_(z)Ga_(1-y-z)Nlayers, where w<u, y and/or x>v, z. The composition and structure of theactive layer are chosen to provide light emission at a preselectedwavelength. The active layer may be left undoped (or unintentionallydoped) or may be doped n-type or p-type. Of course, there can be othervariations, modifications, and alternatives.

In a specific embodiment, the active region can also include an electronblocking region, and a separate confinement heterostructure. In someembodiments, an electron blocking layer is preferably deposited. Theelectron-blocking layer may comprise Al_(s)In_(t)Ga_(1-s-t)N, where 0≦s,t, s+t≦1, with a higher bandgap than the active layer, and may be dopedp-type. In one specific embodiment, the electron blocking layercomprises AlGaN. In another embodiment, the electron blocking layercomprises an AlGaN/GaN super-lattice structure, comprising alternatinglayers of AlGaN and GaN, each with a thickness between about 0.2 nm andabout 5 nm. Of course, there can be other variations, modifications, andalternatives.

As noted, the p-type gallium nitride structure, which can be a p-typedoped AlqInrGa_(1-q-r)N, where 0≦q, r, q+r≦1, layer is deposited abovethe active layer. The p-type layer may be doped with Mg, to a levelbetween about 10¹⁶ cm⁻³ and 10²² cm⁻³, and may have a thickness betweenabout 5 nm and about 1000 nm. The outermost 1-50 nm of the p-type layermay be doped more heavily than the rest of the layer, so as to enable animproved electrical contact. In a specific embodiment, the laser stripeis provided by an etching process selected from dry etching or wetetching. In a preferred embodiment, the etching process is dry, but canbe others. The device also has an overlying dielectric region, whichexposes 213 contact region. In a specific embodiment, the dielectricregion is an oxide such as silicon dioxide, but can be others. Ofcourse, there can be other variations, modifications, and alternatives.

In a specific embodiment, the metal contact is made of suitablematerial. The reflective electrical contact may comprise at least one ofsilver, gold, aluminum, nickel, platinum, rhodium, palladium, chromium,or the like. The electrical contact may be deposited by thermalevaporation, electron beam evaporation, electroplating, sputtering, oranother suitable technique. In a preferred embodiment, the electricalcontact serves as a p-type electrode for the optical device. In anotherembodiment, the electrical contact serves as an n-type electrode for theoptical device. Of course, there can be other variations, modifications,and alternatives. Further details of the cleaved facets can be foundthroughout the present specification and more particularly below.

FIG. 3 is a cross-sectional view photograph of a c-direction cleavedfacet for a laser device according to an embodiment of the presentinvention. This diagram is merely an example, which should not undulylimit the scope of the claims herein. One of ordinary skill in the artwould recognize other variations, modifications, and alternatives. Asshown, the c-direction cleaved facet is smooth and provides a suitablemirror surface. Details of the top-view of the laser device are providedbelow.

FIG. 4 is a top-view diagram of a laser device according to anembodiment of the present invention. This diagram is merely an example,which should not unduly limit the scope of the claims herein. One ofordinary skill in the art would recognize other variations,modifications, and alternatives. As shown, the laser stripe isconfigured in the c-direction, which has a projection normal to thec-direction. As shown, the top-view of the gallium nitride substrate isof a slight mis-cut or off-cut surface region orientation according to aspecific embodiment.

A method of processing a laser device according to one or moreembodiments may be outline as follows, see also FIG. 5:

1. Start;

2. Provide processed substrate including laser devices with ridges;

3. Thin substrate from backside;

4. Form backside n-contact;

5. Scribe pattern for separation of the laser devices configured in barstructures;

6. Break scribed pattern to form a plurality of bar structures;

7. Stack bar structures;

8. Coat bars structures;

9. Singulate bar structures into individual dies having laser device;and

10. Perform other steps as desired.

The above sequence of steps is used to form individual laser devices ona die from a substrate structure according to one or more embodiments ofthe present invention. In one or more preferred embodiments, the methodincludes cleaved facets substantially parallel to each other and facingeach other in a ridge laser device configured on a non-polar galliumnitride substrate material. Depending upon the embodiment, one or moreof these steps can be combined, or removed, or other steps may be addedwithout departing from the scope of the claims herein. One of ordinaryskill in the art would recognize other variations, modifications, andalternatives. Further details of this method are provided throughout thepresent specification and more particularly below.

FIG. 6 is a simplified illustrating of a substrate thinning processaccording to an embodiment of the present invention. This diagram ismerely an illustration and should not unduly limit the scope of theclaims herein. One of ordinary skill in the art would recognize othervariations, modifications, and alternatives. In a specific embodiment,the method begins with a gallium nitride substrate material includinglaser devices and preferably ridge laser devices, but can be others. Thesubstrate has been subjected to frontside processing according to aspecific embodiment. After frontside processing has been completed, oneor more of the GaN substrates are mounted frontside down onto a sapphirecarrier wafer or other suitable member. As an example, the method usesCrystalbond 509, which is a conventional mounting thermoplastic. Thethermoplastic can be dissolved in acetone or other suitable solvent. Ofcourse, there can be other variations, modifications, and alternatives.

In a specific embodiment, the carrier wafer is mounted to a lapping jig.An example of such lapping jig is made by Logitech Ltd. (Logitech) ofthe United Kingdom, or other vendor. The lapping jig helps maintainplanarity of the substrates during the lapping process according to aspecific embodiment. As an example, the starting thickness of thesubstrates are ˜325 um+/−20 um, but can be others. In a specificembodiment, the method laps or thins the substrates down to 70-80 umthickness, but can also be thinner or slightly thicker. In a preferredembodiment, the lapping jig is configured with a lapping plate, which isoften made of a suitable material such as cast iron configured with aflatness of less than 5 um, but can be others. Preferably, the methoduses a lapping slurry that is 1 part silicon carbide (SiC) and 10 partswater, but can also be other variations. In a specific embodiment, theSiC grit is about Sum in dimension. In one or more embodiments, thelapping plate speed is suitable at about 10 revolutions per minute.Additionally, the method can adjust the lapping jig's down pressure toachieve a desired lapping rate, such as 2-3 um/min or greater orslightly less according to one or more embodiments.

In a specific embodiment, the present method includes a lapping processthat may produce subsurface damage in the GaN material to causegeneration of mid level traps or the like. The midlevel traps may leadto contacts having a Schottky characteristic. Accordingly, the presentmethod includes one or more polishing processes such that ˜10 um ofmaterial having the damage is removed according to a specificembodiment. As an example, the method uses a Politex™ polishing pad ofRohm and Haas, but can be others, that is glued onto a stainless steelplate. A polishing solution is Ultrasol300K manufactured by EminessTechnologies, but can be others. The Ultra-Sol 300K is a high-puritycolloidal silica slurry with a specially designed alkaline dispersion.It contains 70 nm colloidal silica and has a pH of 10.6, but can beothers. The solids content is 30% (by weight). In a specific embodiment,the lapping plate speed is 70 rpm and the full weight of the lapping jigis applied. In a preferred embodiment, the method includes a polishingrate of about ˜2 um/hour, but can be others. Of course, there can beother variations, modifications, and alternatives.

In other embodiments, the present invention provides a method forachieving high quality n-type contacts for m-plane GaN substratematerial. In a specific embodiment, the method provides contacts thatare rough to achieve suitable ohmic contact. In a specific embodiment,the roughness causes exposure of other crystal planes, which lead togood contacts. In another embodiment, the present method includes alapped surface, which is rough in texture to expose more than one ormultiple different crystal planes. In other embodiments, lapping may befollowed by etching such as dry etching and/or wet etching. In aspecific embodiment, etching removes the subsurface damage, however, itis likely not to planarize the surface like polishing. Of course, therecan be other variations, modifications, and alternatives.

In a preferred embodiment the sample is subjected to a lapping step, apolishing step, and is then subjected to the laser scribe. Dependingupon the embodiment, one or more steps can be added or removed ormodified. Of course, there can be other variations, modifications, andalternatives.

FIG. 7 is a simplified diagram illustrating a backside n-contact methodaccording to one or more embodiments. This diagram is merely anillustration and should not unduly limit the scope of the claims herein.One of ordinary skill in the art would recognize other variations,modifications, and alternatives. After the thinning process is complete,the method forms n-contacts on the backside of the substrates accordingto one or more embodiments. At this point, the thinned substrates arestill mounted to and maintained on the sapphire wafer. In a preferredembodiment, the thinned substrates are “batch processed” for efficiencyand handling. In a specific embodiment, the method using batchprocessing helps prevent any damage associated with handling very thin(e.g., 60-80 um) substrates.

As an example, the backside contact includes about 300 Å Al/3000 Å Au orother suitable materials. In a specific embodiment, the contact is astack of metals that are deposited by e-beam evaporation or othersuitable techniques. In a preferred embodiment and prior to the metalstack deposition, the method includes use of a wet etch such as anhydrofluoric acid wet etch to remove any oxides on the surface. In aspecific embodiment, the metal stack is preferably not annealed orsubjected to high temperature processing after its formation. Of course,there can be other variations, modifications, and alternatives.

FIG. 8 is a simplified diagram illustrating a scribe and break operationaccording to one or more embodiments. This diagram is merely anillustration and should not unduly limit the scope of the claims herein.One of ordinary skill in the art would recognize other variations,modifications, and alternatives. After the n-contact is formed, thesubstrates are demounted from the sapphire carrier wafer and cleaned inacetone and isopropyl alcohol according to a specific embodiment. Thesubstrates are then mounted onto vinyl tape for the scribe and breakprocess depending upon the embodiment. In a preferred embodiment, thetape does not leave any residue on the laser bars, which aresubstantially free from such residues, which are often polymeric innature or particulates.

Next, the method includes one or more scribing processes. In a specificembodiment, the method includes subjecting the substrates to a laser forpattern formation. In a preferred embodiment, the pattern is configuredfor the formation of a pair of facets for one or more ridge lasers. In apreferred embodiment, the pair of facets face each other and are inparallel alignment with each other. In a preferred embodiment, themethod uses a UV (e.g., 355 nm) laser to scribe the laser bars. In aspecific embodiment, the laser is configured on a system, which allowsfor accurate scribe lines configured in one or more different patternsand profiles. In one or more embodiments, the scribing can be performedon the backside, frontside, or both depending upon the application. Ofcourse, there can be other variations, modifications, and alternatives.

In a specific embodiment, the method uses backside scribing or the like.With backside scribing, the method preferably forms a continuous linescribe that is perpendicular to the laser bars on the backside of theGaN substrate. In a specific embodiment, the scribe is generally 15-20um deep or other suitable depth. Preferably, backside scribing can beadvantageous. That is, the scribe process does not depend on the pitchof the laser bars or other like pattern. Accordingly, backside scribingcan lead to a higher density of laser bars on each substrate accordingto a preferred embodiment. In a specific embodiment, backside scribing,however, may lead to residue from the tape on one or more of the facets.In a specific embodiment, backside scribe often requires that thesubstrates face down on the tape. With frontside scribing, the backsideof the substrate is in contact with the tape. Of course, there can beother variations, modifications, and alternatives.

In a preferred embodiment, the present method uses frontside scribing,which facilitates formation of clean facets. In a specific embodiment,the frontside scribing process is preferably used. In a specificembodiment, the method includes a scribe pattern to produce straightcleaves with minimal facet roughness or other imperfections. Furtherdetails of scribing are provided below.

Scribe Pattern: The pitch of the laser mask is about 200 um, but can beothers. The method uses a 170 um scribe with a 30 um dash for the 200 umpitch. In a preferred embodiment, the scribe length is maximized orincreased while maintaining the heat affected zone of the laser awayfrom the laser ridge, which is sensitive to heat.

Scribe Profile: A saw tooth profile generally produces minimal facetroughness. It is believed that the saw tooth profile shape creates avery high stress concentration in the material, which causes the cleaveto propagate much easier and/or more efficiently.

In a specific embodiment, the present method provides for a scribesuitable for fabrication of the present laser devices. As an example,FIG. 9 illustrates cross-sections of substrate materials associated with(1) a backside scribe process; and (2) a frontside scribe process. Ofcourse, there can be other variations, modifications, and alternatives.

Referring now to FIG. 10, the method includes a breaking process to forma plurality of bar structures. This diagram is merely an illustrationand should not unduly limit the scope of the claims herein. One ofordinary skill in the art would recognize other variations,modifications, and alternatives. After the GaN substrates are scribed,the method uses a breaker to cleave the substrates into bars. In aspecific embodiment, the breaker has a metal support that has a gapspacing of 900 um. The substrate is positioned over the support so thatthe scribe line is in the centered. A suitably sharp ceramic blade, thenapplies pressure directly on the scribe line causing the substrate tocleave along the scribe line.

FIG. 11 is a simplified diagram illustrating a stacking and coatingprocess according to one or more embodiments. Again, this diagram ismerely an illustration and should not unduly limit the scope of theclaims herein. One of ordinary skill in the art would recognize othervariations, modifications, and alternatives. After cleaving, the barsare stacked in a fixture that allows for coating the front facet andback facet, which are in parallel alignment with each other and facingeach other. The front facet coating films can be selected from anysuitable low reflectance design (AR design). The AR design includes aquarterwave coating of Al₂O₃ capped with a thin layer of HfO₂ accordingto a specific embodiment. The Al₂O₃ coating is a robust dielectric, andHfO₂ is dense, which helps environmentally passivate and tune thereflectance of the front facet. These coating films are preferablydeposited by e beam evaporation. In a specific embodiment, the backfacet is coated with a high reflectance HR design. The HR designincludes several quarterwave pairs of SiO₂/HfO₂. In a specificembodiment, roughly 6-7 pairs may be used to achieve a reflectance over99%. Of course, there can be other variations, modifications, andalternatives.

In a preferred embodiment, the method uses a suitable deposition systemconfigured for deposition of each of the facets without breaking vacuum.The deposition system includes a dome structure with sufficient heightand spatial volume. The system allows for the plurality of barsconfigured in a fixture to be flipped from one side to another side andto expose the back facet and the front facet according to a specificembodiment. In a preferred embodiment, the method allows for firstdeposition of the back facet, reconfiguring the bar fixture to exposethe front facet, and second deposition of the front facet withoutbreaking vacuum. In a preferred embodiment, the method allows fordeposition of one or more films on front and back without breakingvacuum to save time and improve efficiency. Other embodiments can breakvacuum. Of course, there can be other variations, modifications, andalternatives.

FIG. 12 illustrates a method directed to singulate bars into a pluralityof die according to a specific embodiment. This diagram is merely anillustration and should not unduly limit the scope of the claims herein.One of ordinary skill in the art would recognize other variations,modifications, and alternatives. After the facets of the bars have beencoated, the method includes testing the laser devices in bar form priorto die singulation. In a specific embodiment, the method singulates thebars by performing a scribe and break process (similar to the facetcleave). Preferably, the method forms a shallow continuous line scribeon the top side of the laser bar according to a specific embodiment. Thewidth of each die is about 200 um, which may reduce the support gap to300 um or so. After the bars have been cleaved into individual die, thetape is expanded and each of the die is picked off of the tape. Next,the method performs a packing operation for each of the die according toone or more embodiments.

The above sequence of steps is used to form individual laser devices ona die from a substrate structure according to one or more embodiments ofthe present invention. In one or more preferred embodiments, the methodincludes cleaved facets substantially parallel to each other and facingeach other in a ridge laser device configured on a non-polar galliumnitride substrate material. Depending upon the embodiment, one or moreof these steps can be combined, or removed, or other steps may be addedwithout departing from the scope of the claims herein. One of ordinaryskill in the art would recognize other variations, modifications, andalternatives. Further details of this method are provided throughout thepresent specification and more particularly below.

In a preferred embodiment, the present invention provides a method forforming a contact (e.g., n-type) to one or more of the present nonpolarlaser diodes, light emitting diodes, and other applications using alaser scribe technique. We discovered that it was difficult to form ann-contact to nonpolar and semipolar GaN surfaces after wafering,lapping, or polishing. Each of these processes creates surfacecrystalline damage that can result in a Schottky contact. It was desiredto propose techniques to remove the crystalline damage and/or improvecontact characteristics. Further, it is believed that making a goodn-contact to nonpolar substrates is a difficult task even without thepresence of crystal damage.

In one or more embodiments, the present method uses wet etching and/ordry etching of the damaged surface prior to depositing the n-contact toremove the damage. However, there are few wet chemistries that actuallyetch GaN, and the wet etches that we evaluated actually resulted in adegraded n-contact resistance. More specifically, as examples, KOH,HPO₄, and HNO₃ based wet etch treatments were used. In one or moreembodiments, the present method uses dry etching including etching gasessuch as Cl₂, Ar, and BCl₃, which slightly improved the surface, but thecontacts were still slightly Schottky. Of course, there can be othervariations, modifications, and alternatives.

In one or more preferred embodiments, the present method uses a laserscribing technique for contact formation. After repeated efforts to formohmic contacts to the bulk GaN substrates, we discovered that if thesubstrate is laser scribed before or after the contact metallization isdeposited, the contact resistance can be greatly reduced. That is, bylaser scribing the backside, we made desirable ohmic contacts tosurfaces that have been subjected to a lapping process, a polishingprocess, both a lapping and a polishing process, and KOH etched,although there may also be other combinations. Further details of thepresent laser scribing technique can be found throughout the presentspecification and more particularly below.

In a preferred embodiment, the present invention uses a laser scribertechnique and system. The laser scriber system is generally used in ascribe and break process, which is similar to the one for creating laserdiode facets or to singulate laser die and LED die, according to one ormore embodiments. As an example, the scribe tool is configured with a355 nm UV laser and an XY table. The scribe tool is configured to formvarious scribe patterns and depths in the GaN substrate material. Ofcourse, other scribe tools can be used.

In one or more embodiments, the scribe process can be applied to eitheror both pre-metallization and post-metallization. We initiallydiscovered the scribe process when singulating laser die using a laserscribe on the backside of laser devices, which were metalized. Wediscovered a large voltage drop across the laser device when using thelaser scribe process for die singulation. It was initially thought thelaser scribe was locally alloying the material in the scribe line. Wealso evaluated the laser scribe pre-metallization and observed similarcharacteristics, so it is modifying the GaN as well.

It is not clear about the mechanism that generates the good ohmiccontact from laser scribing. The laser scribing could be benefiting thecontact through locally heat treatment of the semiconductor by annealingdamaged material, by creating some beneficial elemental diffusionprofile, creating a gallium rich metallic surface, recrystallizing thedamaged surfaces, or other influences. The laser scribe could alsocreate a gallium rich spike that penetrates the damaged material intothe undamaged bulk material. Or it could be something entirely differentthat is independent of damage, such as exposing one or more additionalcrystallographic planes to contact or creating some highly conductivelayer in the vicinity of the scribe. That is, the overlying contactmetallization is formed overlying the substrate, edges of scribe region,and bottom region of trenched region. In one or more embodiments, thebottom and/or edges may expose additional crystallographic planes. Ofcourse, the benefit could be resulting from any combination of the aboveor others characteristics. According to one or more embodiments, thepresent backside contact process for lasers is described below.

-   -   1. Lap GaN substrates with a 5 um SiC (e.g., Logitech) or        suitable slurry on cast iron lapping plate from ˜330 um to 80        um, but can be others;    -   2. Polish substrates with colloidal silica (e.g., Eminess Tech,        300K or others) on Politex (e.g., Rodel) pad from 80 um to 70        um, but can be others;    -   3. Perform backside laser scribe on the entire backside of the        substrate parallel to the laser ridges: 2 to 20 mm/s feed rate,        10 to 50 mW power, 10 to 100 um pitch (although there may be        other variation, modifications, and alternatives). This        generates a continuous scribe that is ˜3-5 um deep.    -   4. HCl dip to remove excess surface slag;    -   5. HF dip to remove colloidal silica from polish;    -   6. Sputter Al/Ni/Au to form contact region; and    -   7. Perform other steps, as desired

Although the above has been described in terms of one or more specificembodiments, there could be many other variations, alternatives, andmodifications. Such alternative embodiments may include but are notlimited to:

-   -   1. Using any metal stack as the n-contact, e.g., Al/Ni/Au,        Al/Pt/Au, Ti/Pt/Au;    -   2. Performing the laser scribe after the metal is deposited in a        different sequence from the above;    -   3. Not including a lapping and/or polishing step, which may also        be replaced with one or more other processes;    -   4. Lapping to different thicknesses;    -   5. Using some other agent(s) to remove surface slag such as HF        or other combinations of etchants, cleaning solutions, slurries,        and the like;    -   6. Not removing the surface slag;    -   7. Using alternative laser power settings;    -   8. Using a laser scribe pattern;    -   9. Using nonpolar or semipolar substrates;    -   10. Using low laser power settings to locally heat the material,        not create a scribe; and    -   11. Other desired processes.

The above sequence of steps is used to form individual laser devices ona die from a substrate structure according to one or more embodiments ofthe present invention. In one or more preferred embodiments, the methodincludes laser scribed backside regions for improved contact formationconfigured on a non-polar gallium nitride substrate material. Dependingupon the embodiment, one or more of these steps can be combined, orremoved, or other steps may be added without departing from the scope ofthe claims herein. One of ordinary skill in the art would recognizeother variations, modifications, and alternatives. Further details ofthis method are provided throughout the present specification and moreparticularly below.

In one or more other embodiments, the present invention performsbackside die singulation with the laser scriber for only die singulationpurposes. In one or more embodiments, the present method and structurecan provide for a laser scribed contact, which has improvedconductivity. Of course, there can be other variations, modifications,and alternatives. Further details of the present method can be describedby way of the Figures below.

FIGS. 13 to 18 illustrate a simplified laser scribe process forimproving contact regions of an optical device according to one or moreembodiments of the present invention. These diagrams are merelyillustrations and should not unduly limit the scope of the claimsherein. One of ordinary skill in the art would recognize othervariations, modifications, and alternatives.

Mount to Carrier

After frontside processing, the GaN substrate is mounted frontside downonto a sapphire wafer with Crystalbond 509.

Lapping

The GaN substrate is thinned from ˜330 um to 80 um by lapping with 5 umSiC on a cast iron plate. We use a Logitech lapping system and jig toperform this process. Note that the surface is rough after this process.

Polish

To remove surface roughness and subsurface damage, the GaN substrate ispolished from 80 um to 70 um by polishing with colloidal silica on apolishing pad. We use a Logitech lapping system and jig to perform thisprocess. The colloidal silica (300K) is manufactured by Eminess and pad(Politex) is manufactured by Rodel. Note that the surface is smooth, butsmall amounts of colloidal silica is still attached to the surface.

Laser Scribe

The laser scribe is performed on the backside of the substrate. Thescribe parameters are: power: 25 mW, scan speed: 10 mm/s, pattern:continuous line on a 40 um pitch these lines are parallel to the ridgeson the frontside. The scribe depth is ˜3-5 um deep

HCl and HF Dip

After the laser scribe, there is slag present on the surface. This isremoved by a 5 min dip in HCl. In addition, we remove the colloidalsilica with a 1 min dip in HF. This also helps remove any native oxideson the GaN surface.

N-Contact Deposition

The N-contact is deposited with our DC magnetron sputter system. Themetal stack is the following: Al/Ni/Au 300/200/3000 A.

The above sequence of steps is used to form individual laser devices ona die from a substrate structure according to one or more embodiments ofthe present invention. In one or more preferred embodiments, the methodincludes laser scribed backside regions for improved contact formationconfigured on a non-polar gallium nitride substrate material. In one ormore embodiments, one or more of the scribe lines is arranged in atleast one spatial configuration including an annular segment, a circularsegment, a straight line segment, an irregular line segment, or othercombinations. Depending upon the embodiment, one or more of these stepscan be combined, or removed, or other steps may be added withoutdeparting from the scope of the claims herein. One of ordinary skill inthe art would recognize other variations, modifications, andalternatives. Further details of this method are provided throughout thepresent specification and more particularly below.

Example

FIGS. 19, 20(A), and 20(B) are simplified diagram illustratingexperimental results of a laser scribing process for contact formationaccording to one or more examples of the present invention. Thesediagrams are merely illustrations and should not unduly limit the scopeof the claims herein. One of ordinary skill in the art would recognizeother variations, modifications, and alternatives.

FIG. 19 shows an IV curve from a set of Transmission Line Models (TLM's)that were fabricated on top of 4 different GaN backside surfaces:lapped, lapped and laser scribed, lapped and polished, and lapped,polished and laser scribed. As used herein, TLM stands for TransmissionLine Model, which is a measure technique for resistance of contactsalong with the sheet resistance of the one or more materials having thedeposited metallization contacts. Typically the measurements areperformed by varying the distances between the two metal contacts andplotting resistance versus distance of the contacts. From the line thatis formed on the plot, the contact resistance and the sheet resistanceare deduced. As shown are current versus voltage curves in the plots.The curves are for the different n-contact schemes on the same orsimilar geometry/distance TLM feature deposited on the samples. Thelower voltage for a fixed current or higher current for a fixed voltagefor the laser scribed samples indicates lower resistance, which islikely mainly attributed to the lower contact resistance, but could alsohave some contribution from lower sheet resistance. The TLM pattern iscircular with inner diameter of 100 um and 8 um spacing. For both lappedsubstrates and lapped and polished substrates, the contacts weredrastically improved changing from a Schottky characteristic to an ohmiccharacteristic. Of course, there can be other variations, modifications,and alternatives.

FIG. 20(A) shows a cross-sectional optical image of the laser facet. Theridge can be seen on the front side (top) and the n-contact laserscribes can be seen on the backside (bottom). One can also see the frontside (top) laser scribes that were used to create the facet. FIG. 20(B)shows an optical image of laser scribes on the backside of the laser.These scribes are spaced on a 40 um pitch and are continuous across thebackside of the laser. Of course, there can be other variations,modifications, and alternatives.

In one or more embodiments, the present method is configured for laserdiodes operating in the 390-420 nm range, 420-460 nm range, 460 nm-500nm range, 500-540 nm range, and +540 nm range, combinations, and others.As an example, the laser diodes can also be configured with one or moreof the following parameters:

-   -   Operating Current density range: 0.5-2 kA/cm2, 2-4 kA/cm2, 4-8        kA/cm2, 8-16 kA/cm2, +16 kA/cm2;    -   Operating Voltage range: 4-5V, 5-6V, 6-7V, 7-9V, +9V;    -   Series resistance range: 1-3 ohm, 3-6 ohm, 6-10 ohm, 10-15 ohm,        +15 ohm;    -   Operating output power range: 0.5-5 mW, 5-25 mW, 25-75 mW,        75-150 mW, 150-500 mW, 500 mW-1 W, 1-5 W, +5 W; and

Other desirable features, including combinations.

In alternative embodiments, the laser diodes vary and may include singlelateral mode, multi-lateral mode, laser arrays for high power, edgeemitting, vertical cavity (VCSEL), combinations, and the like.

In alternative embodiments, the present method and device are configuredfor LEDS operating in the 390-420 nm range, 420-460 nm range, 460 nm-500nm range, 500-540 nm range, and +540 nm range, combinations, and thelike. As an example, the laser diodes can also be configured with one ormore of the following parameters:

-   -   Operating Current density range: 0.1-0.3 kA/cm2, 0.3-0.5 kA/cm2,        0.5-1.0 kA/cm2, 1.0-2.0 kA/cm2, +2.0 kA/cm2;    -   Operating Voltage range (per single LED): 2.2-2.8V, 2.8-3.2V,        3.2-3.5V, 3.5-3.8V, 3.8-4.5V, 4.5-6.0V, +6V;    -   Operating Voltage range (for series connected LEDs or some other        high voltage config): 4-12V, 12-24V, 24-48V, 48-96V, 96-140V,        +140V;    -   Series resistance range: 0.1-0.3 ohm, 0.3-0.6 ohm, 0.6-1.0 ohm,        1-2 ohm, 2-5 ohms, 5-10 ohm, +10 ohm;    -   Operating output power range: 200-300 mW, 300-500 mW, 500 mW-1        W, 1-2 W, 2-5 W, 5-10 W, +10 W; and

Other desirable features, including combinations.

In alternative embodiments, the LEDs vary and may include low power,high power, different configurations of electrodes and active regions,combinations, and the like.

While the above is a full description of the specific embodiments,various modifications, alternative constructions and equivalents may beused. Therefore, the above description and illustrations should not betaken as limiting the scope of the present invention which is defined bythe appended claims.

1-11. (canceled)
 12. A method for forming optical devices comprising:providing a gallium nitride substrate member having a crystallinesurface region and a backside region; subjecting the backside region toa laser scribing process to form a plurality of scribe regions on thebackside region; forming a metallization material overlying the backsideregion including the plurality of scribe regions; and removing at leastone optical device using at least one of the scribe regions.
 13. Themethod of claim 12 further comprising: subjecting the backside regionincluding the plurality of scribe regions to a first treatment processto remove native oxide from the backside region; and subjecting thebackside region including the plurality of scribe regions to a secondtreatment process to remove one or more particles of metallization orlaser slag from a vicinity of the scribe region.
 14. (canceled)
 15. Themethod of claim 13 wherein the second treatment process comprises an HCletch process; and wherein the removing comprises one or more singulationprocesses.
 16. (canceled)
 17. The method of claim 12 wherein themetallization comprises at least one of an Al/Ni/Au stack, an Al/Pt/Austack, or a Ti/Pt/Au stack. 18-19. (canceled)
 20. The method of claim 12further comprising lapping and polishing the backside region before thelaser scribing process.
 21. The method of claim 12 wherein themetallization material is an n-contact region having a desiredresistivity.
 22. The method of claim 12 wherein the optical device ischaracterized by an operating voltage of less than 7.5V, less than 6.5V,less than 5.5V, less than 4.5V, or less than 3.5V. 23-26. (canceled) 27.The method of claim 12 wherein the laser scribing process anneals one ormore portions of the gallium nitride substrate.
 28. The method of claim12 wherein the laser scribing process causes formation of a higherimpurity region within a vicinity of one or more scribe regions.
 29. Themethod of claim 12 wherein the metallization material forms overlyingeach of the scribe regions including edges of the scribe region.
 30. Themethod of claim 12 wherein each of the scribe regions forms a recessedregion extending partially through a thickness of the gallium nitridesubstrate.
 31. A method for forming optical devices comprising:providing a gallium nitride substrate member having a crystallinesurface region and a backside region; forming a metallization materialoverlying the backside region including the plurality of scribe regions;subjecting the backside region to a laser scribing process to form aplurality of scribe regions on the backside region; and removing atleast one optical device using at least one of the scribe regions. 32.The method of claim 31 wherein the optical device comprises a lightemitting diode device.
 33. The method of claim 31 wherein the opticaldevice comprises a laser device.
 34. The method of claim 31 wherein thecrystalline surface region is configured in at least one of a non-polarorientation, a semi-polar orientation, an m-plane orientation having a+/−6 degree off-cut, or a {20-21} orientation. 35-38. (canceled)
 39. Themethod of claim 31 wherein one or more of the scribe lines is arrangedin at least one spatial configuration including an annular segment, acircular segment, a straight line segment, an irregular line segment, ina parallel manner, or other combinations.
 40. The method of claim 31wherein the laser scribing process is provided form a 355 nm UV source.41. A method for forming optical devices comprising: providing a galliumnitride substrate member having a crystalline surface region and abackside region, the crystalline surface region configured in anon-polar or semi-polar orientation; forming one or more active regionsconfigured to emit electromagnetic radiation for an optical device;forming a metallization material overlying a surface region; subjectingthe surface region to a laser treatment process to change an operatingvoltage of the optical device from a first value to a second value, thesecond value being less than the first value by at least 10 percent andcausing formation of at least one scribe region on the surface region;and removing at least the optical device using at least the scriberegion.
 42. The method of claim 41 wherein the forming of themetallization material is provided before or after the laser treatmentprocess; and wherein the removing process further comprising a breakingprocess.
 43. (canceled)
 44. The method of claim 41 wherein the surfaceregion comprises at least the back side region or the front side region;and wherein the electromagnetic radiation comprises substantially 405 nmemission or substantially 485 nm emission or substantially a range fromabout 495 nm to about 535 nm emission. 45-47. (canceled)